FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: Katz427 on October 05, 2024, 03:33:39 PM
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I have been assembling a 427, with a BBM block, block is 5 years old but never assembled. I have things mocked up, camshaft installed, turns smoothly. Waiting on pushrods. I installed the distributor, (Mallory, that ran recently in a 390), and the distributor went in, however the camshaft is locked up tight. Can't turn it. Pulled the distributor out, camshaft turns smoothly. Took off the cam thrust plate, removed intake manifold, and the distributor does "seat" where the counter bore is but, then again the camshaft will not turn. It appears that the teeth are engaged too deep, from what I see. Anyone have this problem?
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Which front cam bearing did you use?
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Hi Brent, the narrow one, followed your advice. That seems fine, 0.005 end play.
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I can't turn the camshaft, but some paint on distributor gear shows the camshaft gear making contact with the "root" of the distributor gear. The distributors available to me, one is a electronic with a hardened ( melonized) gear, the Mallory has whatever came from the factory, ( dual point).
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Both distributors do the same thing?
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Yes Brent, though the old Mallory, fits a bit better, going into the block. However, camshaft will not budge, with either installed.
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Is the timing set on? You just have the cam in the block with the thrust plate on and the distributor in it?
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Yes Brent ,I removed the timing set, checked camshaft end play, again, then tried the distributors again with no luck. Won't turn.
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With the distributor seated, can you pull up on the rotor/is there end play in the distributor?
If not, then we need to start looking at dimensions on machined parts. I’ve got a couple of BBM blocks here that I can compare with if need be.
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No end play when distributor seated in block. Everything is up tight, no camshaft end play either. It does seem, that the bore for the distributor, perhaps might be off a bit (a tolerance stack up). I did see one forum where someone was saying their aftermarket FE block was off, with the bore for the distributor. Don't know , other than his comment was he "hand dressed" a bronze distributor gear, to get around the problem. Brent,THANKS for your help!
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You could shim the distributor up a hair id think. The distributor seal can be a little forgiving.
Aftermarket blocks are fun. Wait until you prime the oil pump and oil starts coming out of random places on the outside of the block.
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It seems that the gear on the camshaft, the teeth are maybe too thick, compared to an older Engle camshaft I have here. I don't know if there is anything that can be done, to correct this. I did see a post on Yellow bullet where a gent with an Olds engine had a similar problem, the cam was replaced, and problem solved. Yes, I hope, that this block doesn't leak, it was pressure tested, but that was water jackets. Thanks for the feedback.
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I was going to say earlier, you got another cam you can install to test?
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Further investigation finds that the "hole" for the distributor is off about .016" to the front of the block ,and .005" closer to the camshaft. Finally I installed the whole shibang, into a NOS 428 block, and everything turns "smoothly". So in final analysis it is the block distributor hole that is off enough so that this right angle drive locks up. I'm not sure this is fixable. With a crank trigger ignition, and a Avaid belt drive outside pump it could be useable.
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A problem like you describe is fixable. It could be bored bigger at the correct location, and the distributor hole and pilot sleeved to correct it. Never seen that before.
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Is the dist hole also off or just the lower guild hole?
It could be fixed on a mill, now that you know what the error is, by boring and sleeving it.
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It seems that the gear on the camshaft, the teeth are maybe too thick, compared to an older Engle camshaft I have here. I don't know if there is anything that can be done, to correct this. I did see a post on Yellow bullet where a gent with an Olds engine had a similar problem, the cam was replaced, and problem solved. Yes, I hope, that this block doesn't leak, it was pressure tested, but that was water jackets. Thanks for the feedback.
Wow. You never know what you’re gonna get.
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The whole bore for the distributor hole is off. It would require what Blair is suggesting, unfortunately. The bore for the distributor, is 0.016" closer to the machined front surface, where the camshaft thrust plate is attached, than the measurement I got from the NOS 428 block.
It would be nice to have a drawing of block showing the factory dimensions.
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Just a thought……..you could turn .016 off the face of the camshaft so it can move forward the .016, if you are confident in the number. The .016 won’t hurt anything else. The lobes are wide enough, and the bearings are wide enough that it should fix your problem, if that is for sure your problem. I doubt the .005 you mentioned on the other axis would hurt you. That would be the least painful fix. I think if I were you, I would try that, and just for a little help, take some Emory cloth and take .002 off whichever half of the distributor body would move you the right direction. Put moly lube on the cam gear and the whole mess will probably wear in and make itself a home if it turns free on the stand.
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You could also test to see if that works by putting some shims behind the cam retention plate, to space it out .016", or .020" or whatever. If the cam turns like that, then cutting the face of the cam would definitely work.
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It's been a while so the details are fuzzy now but I had something hitting a cam lobe with my BBM block. I put a shim behind the retainer to move the cam forward slightly and it's been fine since.
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I will give it a try. I did allow the cam to move forward, it did allow the distributor to set all the way into the counter bore at the top, ( I have removed the intake manifold) , but, no luck, still locked up. The camshaft moves fine, even moved forward, but install the distributor and locked up. I can see "witness " marks where the camshaft gear is hitting the root of the distributor gear, on the drive side.
Someone directed me too some drawings on the 332-428 FE site, too get some dimensions used to locate the distributor bore. The 428 block, everything just goes together, and rotates easily, the distributor drops right in, camshaft turns.
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To test it, you would need to do as Jay suggested and shim the thrust plate, and put the cam gear back on it and pull it up. With no thrust plate, it will not keep the cam located while you try to turn it. It will just push the cam until it locks up. Try it with your thrust plate and top gear in position.
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Sounds like the camshaft gear may be cut wrong, try it with another old cam known to be ok. might be the cam AND the block dimensions stacking up ? :)
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I believe these are the dimensions that you need.
Correct me if I'm wrong but, I believe the "Front Mfg Hole" is the forward, large hole on the bottom of the block.
The nominal dimensions are .58 x 1.619
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I'm still at it, shimed out the thrust plate, tried a few thicknesses, did allow me to get the distributor seated. However still would lock up. The camshaft gear is hitting the root of the distributor gear. So I took my pattern files and worked on the root of the gear teeth. I finally got the whole shebang to turn. It's a bit rough, but it did make 1 revolution, so I could get a gear pattern to look at. Then I decided to try and old camshaft and the Mallory dual point , and locked up tight. This old camshaft and Mallory distributor turn nicely in the 428 block. I did get a couple drawings, and that distributor hole, is off , closer to the front surface and slightly off the vertical plane IMO. SO that's it. I really have not removed any material from the face of the distributor gear teeth, it's all been at the root, where the camshaft gear has been contacting. I keep looking at the 428 block, maybe I should change to katz428.
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And a big "Thank you " to Frank for the drawings!
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Just a thought, if I was going to take the .016 off the front of the cam, I think I would try it with an old junk cam first to see it it works
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Also, I would take a few thousands of the OD of the dist gear, to make sure it isn't bottoming in the cam gear.
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Still at it, a .010 shim under the camshaft thrust plate, and removing material from the root of the distributor gear, plus taking the sharp edge off the camshaft gear, adds up to the whole,shebang WILL rotate. Still, IMO the lower, pilot hole is off about .005" though that is a tough measurement to get right.
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You could set it in a milling machine, indicate the hole and move off to your .005. Bore a new hole, to a convenient size, like .500 or the Ford FT size of .516 and bush it to the std size of .453. Then, turn the dist housing .010, to fit w/o binding.
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Well finally, success! Distributor spins smoothly and the gear pattern looks decent. Moving the bottom pilot hole about .005 away from the camshaft, and about .004 shim out the camshaft thrust plate, along with some pattern file work on the root of the distributor gear teeth. This block had a couple machining issues from the " getgo ", like the spot face for the side cross bolts was machined on the left side, but only one was machined on the right. ( that was a fairly easy fix). It needed the usual align hone of the mains, and machine the deck, to get it parallel to the mains, the usual stuff. So thanks for the Help, and thank you Frank for those drawings.
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Your very welcome.